Guided missile fuze system

ABSTRACT

1. In a guided missile fuze system of the type wherein electromagnetic energy is radiated and a portion of said radiated energy is returned by a reflecting means for actuating a firing circuit the combination for providing countermeasures against a sweep jammer comprising: A. A FIRST FUZING CHANNEL RESPONSIVE TO SIGNALS RECEIVED IN A FIRST FREQUENCY BAND, B. A FIRST FIRING CIRCUIT, C. A NORMALLY CLOSED RELAY FOR CONNECTING SAID FIRST FUZING CHANNEL TO SAID FIRST FIRING CIRCUIT, D. A SECOND FUZING CHANNEL RESPONSIVE TO SIGNALS RECEIVED IN A SECOND FREQUENCY BAND THAT IS HIGHER IN FREQUENCY THAN SAID FIRST FREQUENCY BAND, E. A SECOND FIRING CIRCUIT, F. A NORMALLY OPEN RELAY FOR CONNECTING SAID SECOND FUZING CHANNEL TO SAID SECOND FIRING CIRCUIT, G. A SIGNAL PROCESSING CHANNEL RESPONSIVE TO SIGNALS RECEIVED IN A THIRD FREQUENCY BAND THAT IS HIGHER IN FREQUENCY THAN SAID SECOND FREQUENCY BAND, H. RELAY ACTUATING MEANS RESPONSIVE TO AN OUTPUT FROM SAID SIGNAL PROCESSING CHANNEL WHEN SIGNALS ARE RECEIVED FROM THE SWEEP JAMMER FOR CLOSING SAID NORMALLY OPEN RELAY FOR A PREDETERMINED PERIOD THAT IS LESS THAN THE TIME FOR THE SWEEP TO TRAVEL FROM SAID SIGNAL PROCESSING CHANNEL TO SAID SECOND FUZING CHANNEL, I. RELAY ACTUATING MEANS RESPONSIVE TO AN OUTPUT FROM SAID SECOND FUZING CHANNEL WHEN SIGNALS ARE RECEIVED FROM THE SWEEP JAMMER FOR OPENING SAID NORMALLY CLOSED RELAY WHEREBY SAID FIRST FIRING CIRCUIT WILL NOT FIRE ON THE JAMMING SIGNAL.

Unite States Patent Beane et al.

GUIDED MISSILE FUZE SYSTEM Inventors: Theodore E. Beane, Upper GwynnedTownship, Montgomery County; Alan L. Kirsch, Dresher, both of Pa.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Feb. 24, 1964 [21] Appl. No.: 347,098

[52] U.S. Cl. l02/70.2 P [51] Int. Cl. F42C 13/04 [58] Field of Search102/192, 70.2, 70.2 P

[56] References Cited UNITED STATES PATENTS 3,018,733 l/l962 Johnsonl02/70.2

Primary Examiner-Harvey E. Behrend Assistant Examiner-C. T. JordanAttorney, Agent, or Firm-Richard S. Sciascia; Joseph M. St. Amand; T. M.Phillips EXEMPLARY CLAIM 1. 1n a guided missile fuze system of the typewherein electromagnetic energy is radiated and a portion of saidradiated energy is returned by a reflecting means for actuating a firingcircuit the combination for providing countermeasures against a sweepjammer comprising:

a. a first fuzing channel responsive to signals received in a firstfrequency band,

b. a first firing circuit,

c. a normally closed relay for connecting said first fuzing channel tosaid first firing circuit,

d. a second fuzing channel responsive to signals received in a secondfrequency band that is higher in frequency than said first frequencyband,

e. a second firing circuit,

f. a normally open relay for connecting said second fuzing channel tosaid second firing circuit,

g. a signal processing channel responsive to signals received in a thirdfrequency band that is higher in frequency than said second frequencyband,

h. relay actuating means responsive to an output from said signalprocessing channel when signals are received from the sweep jammer forclosing said normally open relay for a predetermined period that is lessthan the time for the sweep to travel from said signal processingchannel to said second fuzing channel,

i. relay actuating means responsive to an output from said second fuzingchannel when signals are received from the sweep jammer for opening saidnormally closed relay whereby said first firing circuit will not fire onthe jamming signal.

1 Claim, 3 Drawing Figures DETECTOR C IRCUIT FIRING I CIRCUIT DETECTORCIRCUIT DETECTOR CIRCUIT US. Patent Dec. 30, 1975 3,929,075

I0 [I2 2O MIXER DETECTOR f CIRCuIT FIRING 4 I C|RCU|T ETECTOR CIRCuIT g2FIG. I l6 DETECTOR CIRCuIT ID I2 20 DETECTOR FlR'NG M'XER CIRCUITCIRCUIT /I4 8 DETECTOR CIRCuIT f F! 2 l6 DETECTOR CIRCUIT DETECTORFIRING M'XER C|RCU|T OITQ CIRCUIT NO.I

l8 --0 l4 26 FIG. 3 DETECTOR FIRING CIRCuIT 01/0 CIRCUIT N02 /IS g,

DETECTOR CIRCuIT THEODORE E. BEANE ALAN I KIRSCH INVENTOR. BY yATTORNEYS fuze) de-acti'vate the main fuze channel and activate apassive channel that will fuze on a jamming signal source. 7 M

Another object of the invention is to. provide a fuze system which willfunction. to fuze on a sweep jammer in response to .one or more of theparameters defining a sweep jammer.

A further object of the invention is to provide a fuzing system whichwill fuze on a sweep jammer based on information derived from themodulation bandwidth and power of the jammer.

Still another object of the invention is to provide a fuzing systemwhich will fuze on a sweep jammer based on information derived from thejammer sweep rate.

Other objects and many of the attendant advantages of this inventionwill become readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a block diagram of a fuzing system which relies on jammermodulation bandwidth and power information to fuze on the jammer.

FIGS. 2 and 3 are block diagrams of fuzing systems which rely on thejammer sweep rate information to fuze on the jammer.

Referring now to the drawings, wherein like refer ence charactersdesignate like or corresponding parts throughout the several Figures,there is shown in FIG. 1 a fuzing system having three channels forprocessing signals received at antenna 22. In describing the presentinvention only that portion of the fuzing system is described which isnecessary for receiving and processing reflected signals from a targetor signals received from a jammer. Channel 12 comprises a normaldetector circuit and may be of any of the detector circuits shown anddescribed in copending applcation Ser. No. 789,459, filed .Ian. 27, 1959by Carlton H. Cash. Channel 14 is an automatic gain control circuit andis of the same bandwidth as channel 12 but tuned adjacent to channel 12on the high frequency side. The output from channel 14 is fed to channel12 as a negative feedback so that the gain of channel 12 is reduced asthe strength of jamming signals increase. Relay I8 is also connected tothe output of channel 14 and will operate to de-activate channel 12 whenjamming signal strength is sufficient to saturate channel 12. Channel 16is a passive channel and is tuned to a higher frequency than channel 14.

In operation channels 12 and 14 are operating in the normal manner. Thesignal is received at antenna 22, mixed with a local oscillator signalin mixer to obtain doppler signal which is fed to channel 12 and 14. Ifa signal is received with the proper characteristics, an output willappear in channel 12 which is fed through relay 18 to firing circuit 20.In the presence of sweep jamming, signals from the jammer will saturatechannel 12 and cause dudding. When jamming energy is received in channel14, relay 18 is energized. Functionally, this disconnects channel 12from firing circuit 20 and connects channel 16 to firing circuit 20. Thejamming signal received in channel 16 is processed and provides anoutput signal which activates firing circuit 20. Thus, jamming energymust appear in channels 14 and 16 simultaneously. By tuning channel 16to a frequency greater than that of channel 14 having a bandwidth equalto the expected interference bandwidth plus one-half the bandwidth ofchannel 16, the requirement that the jamming signal simultaneously be inchannel 16 is avoided. Thus, providing control over the minimum noisemodulation bandwidth sweep jammer that will be allowed to trigger thesystem. The following parameters have been found satisfactory inpracticing the invention: Channel 12 centered at the 3rd harmonic of themodulation frequency (3f m 2.505 mc) with a bandwidth of 200 kc. Channel14 is tuned adjacent to the high frequency side of channel 12 with abandwidth of 200 kc. Channel 16 is tuned to 10.8 me with a bandwidthequal to the expected jammer bandwidth.

Referring to FIG. 2 an additional relay 24 is provided to interrupt theconnection of channel 14 to relay 18. Channels 12, 14 and 16 operate atthe same frequencies as in FIG. 2. Channel 16 performs a differentfunction than in the system of FIG. 1. Referring to FIG. 2, theoperation of the system is as follows. The jamming signal enters channel16, which energizes relay 24 and removes channel 14 from the system andleaves channel 12 operating without AGC. Relay 24 is allowed to remainenergized for a time which is less than the time between the leadingedge of the jamming signal leaving channel 16 and entering channel 14.It has been found that with channel 16 operating at a center frequencyof 35 me, firing on a sweep jammer is prevented. For example, with a -mcwide sweep jammer, the sweep enters channel 16 and enables channel 14for L5 milliseconds. By the time the sweep reaches channel 14, relay 24has closed and channel 14 is operating again so that a dudding effectoccurs. Referring to FIG. 3, channels 12 and 14 are operating at thesame frequency as in FIG. 2. Channel 16 is passive and operates at thesame frequency as in FIG. 2. The system of FIG. 3 differs from thesystem of FIG. 2 in the position of relay 22 in the output circuit ofchannel 14. In operation, when sweep jammer enters channel 16, relay 24is energized and remains open for a period of time which is less thanthe time for the sweep to travel from channel 16 to channel 14. Duringthis time interval there will be energy in channel 14 and firing circuit26 will not be activated. When the jammer does enter channel 14, firingis prevented by the AGC action. Firing circuit 26 is provided so thatthe firing threshold for a jammer signal is higher than a target returnsignal. With the gain of channels 12 and 14 approximately equal and thesensitivities of firing circuits 20 and 26 equal, the system issusceptible to firing on a sea-return signal, for example, when sweepjammer entered channel 16. If the threshold of firing circuit 26 is set30 db above firing circuit 20, then it requires a signal in channel 14at the same power level as the jammer, in order to activate firingcircuit 26. This would require the seareturn signal to be 30 db abovetarget threshold to cause detonation in the presence of a sweep jammer,

3 and for such a high sea-return power the system would be dudded.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. it is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. In a guided missile fuze system of the type wherein electromagneticenergy is radiated and a portion of said radiated energy is returned bya reflecting means for actuating a firing circuit the combination forproviding countermeasures against a sweep jammer comprising:

a. first fuzing channel responsive to signals received in a firstfrequency band,

b. a first firing circuit,

c. a normally closed relay for connecting said first fuzing channel tosaid first firing circuit,

d. a second fuzing channel responsive to signals received in a secondfrequency band that is higher in frequency than said first frequencyband,

e. a second firing circuit,

f. a normally open relay for connecting said second fuzing channel tosaid second firing circuit,

g. a signal processing channel responsive to signals received in a thirdfrequency band that is higher in frequency than said second frequencyband,

h. relay actuating means responsive to an output from said signalprocessing channel when signals are received from the sweep jammer forclosing said normally open relay for a predetermined period that is lessthan the time for the sweep to travel from said signal processingchannel to said second fuzing channel,

i. relay actuating means responsive to an output from said second fuzingchannel when signals are received from the sweep jammer for opening saidnormally closed relay whereby said first firing circuit will not fire onthe jamming signal.

1. In a guided missile fuze system of the type wherein electromagneticenergy is radiated and a portion of said radiated energy is returned bya reflecting means for actuating a firing circuit the combination forproviding countermeasures against a sweep jammer comprising: a. firstfuzing channel responsive to signals received in a first frequency band,b. a first firing circuit, c. a normally closed relay for connectingsaid first fuzing channel to said first firing circuit, d. a secondfuzing channel responsive to signals received in a second frequency bandthat is higher in frequency than said first frequency band, e. a secondfiring circuit, f. a normally open relay for connecting said secondfuzing channel to said second firing circuit, g. a signal processingchannel responsive to signals received in a third frequency band that ishigher in frequency than said second frequency band, h. relay actuatingmeans responsive to an output from said signal processing channel whensignals are received from the sweep jammer for closing said normallyopen relay for a predetermined period that is less than the time for thesweep to travel from said signal processing channel to said secondfuzing channel, i. relay actuating means responsive to an output fromsaid second fuzing channel when signals are received from the sweepjammer for opening said normally closed relay whereby said first firingcircuit will not fire on the jamming signal.